We have adapted the turbidimetric assay of immunoglobulins IgG, IgA and IgM to a transfer analyser: Isamat. This reaction takes place in the presence of PEG and the reading is made at 340 nm. The repeatability and reproducibility are satisfactory with a variation coefficient of 2.9% to 7.2%. The correlation with the kinetic method (ICS Beckman) is excellent for IgG and IgA and good for IgM. The protocol established enables eleven assays of three different proteins in one hour. The reduced requirement for pure antiserum and the low sample volume (5 to 10 microliters) make this turbidimetric technique useful in pediatrics.